Biodiesel Production from High Free Fatty Acid-Content Oils: Experimental Investigation of the Pretreatment Step

AbstractBiodiesel has the potential to become a suitable substitute for diesel fuel in the future. However, the reduction of production costs and finding a permanent oil source have remained the two main concerns for this green fuel. The production of biodiesel from acid oils is one of the ways to reduce biodiesel production costs. In addition, high free fatty acid oils are almost never categorized as edible oils. Consequently, this new material has a more reliable margin in debates concerning the security of food, compared to other oils considered in biodiesel production. By considering these important aspects of biodiesel production technology, this study investigates the pretreatment step of biodiesel production from acid oils. In this work, an oil with high free fatty acid content is selected and the main parameters in the biodiesel production reaction are investigated experimentally. The effects of methanol-to-oil ratio (in the range of 0.2 to 1.2 v/v), the amount of catalyst (in the range of 0.5 to 6% v/v) and time (in the range of 20 to 120min) on the progress of the reaction are studied

Improved pitting corrosion resistance of S.S 316L by Pulsed Current Gas Tungsten Arc Welding

In this study, S.S 316L was welded using Direct Current Gas Tungsten Arc Welding (DGTAW) and Pulsed Current Gas Tungsten Arc Welding (PGTAW) methods. Optical observations, scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were employed to study the effect of continuous and pulse currents on microstructure and phase transformation in weld metal (WM). In addition pits morphology were evaluated by SEM. The corrosion behaviour was analyzed using cyclic polarizaton tests and Mott-schottky measurements. The pulse current resulted in finer grain and more ferrite in WM. This can be due to the decrease in heat input and higher cooling rate encouraged by pulse current. Cyclic potentiodynamic polarization tests showed that the WM of sample produced by pulse current show higher corrosion and pitting resistances than that in sample produced by continuous current. The reason is attributed to lower segregation of solute elements such as chromium and molybdenum into the delta-ferrite and also finer grain size produced in WM due to lower heat input and higher cooling rate. Both of these factors increase the stability of passive layer formed. The results showed that the corrosion behaviour of WM in both conditions (pulse and continuous current) is higher than the base metal (BM). This fact is attributed to the presence of ferrite bands formed in BM due to the segregation of alloy elements. The Mott-schottky plots confirmed that the passive layer formed on welded samples was an n-type semiconductor. The results showed that the samples showed less pitting resistance contained more oxygen vacancies in their passive film structure. It is also concluded that the breakdown of passive layer and pitting formation obey point defect model (PDM). Keywords: S.S 316L, Pulsed Current Gas Tungsten Arc Welding (PGTAW), lacy ferrite, vermicular ferrite, Pitting corrosion, Mott- Schottky

The effect of electrolytic solution composition on the structure, corrosion, and wear resistance of peo coatings on az31 magnesium alloy

Plasma electrolytic oxidation coatings were prepared in aluminate, phosphate, and silicate-based electrolytic solutions using a soft-sparking regime in a multi-frequency stepped process to compare the structure, corrosion, and wear characteristics of the obtained coatings on AZ31 magnesium alloy. The XRD results indicated that all coatings consist of MgO and MgF2, while specific products such as Mg2 SiO4, MgSiO3, Mg2 P2 O7, and MgAl2 O4 were also present in specimens based on the selected solution. Surface morphology of the obtained coatings was strongly affected by the electrolyte composition. Aluminate-containing coating showed volcano-like, nodular particles and craters distributed over the surface. Phosphate-containing coating presented a sintering-crater structure, with non-uniform distributions of micro-pores and micro-cracks. Silicate-containing coating exhibited a scaffold surface involving a network of numerous micro-pores and oxide granules. The aluminate-treated sample offered the highest corrosion resistance and the minimum wear rate (5 × 10−5 mm3 N−1 m−1), owing to its compact structure containing solely 1.75% relative porosity, which is the lowest value in comparison with other samples. The silicate-treated sample was degraded faster in long-term corrosion and wear tests due to its porous structure, and with more delay in the phosphate-containing coating due to its larger thickness (30 µm)

Patient Satisfaction With the Family Physician Program in Sabzevar, Iran

BACKGROUND AND OBJECTIVES: Patient satisfaction with the family physician program is an important factor for more favorable treatment results. Evaluation of patient satisfaction improves the services and approximates them to patient's preferences. The family physician program has been executed since late March, 2005 in Iran. This study aimed to measure patient satisfaction with family physician services and determines factors affecting the level of satisfaction in order to propose appropriate suggestions for providing medical services based on patients' expectations. METHODS: Forty-one centers provide healthcare services in rural and urban areas. The participants in this study comprised 1263 people. The data were collected by an inventory with 11 items about demographic specifications, waiting time and the importance of physician's sex and 40 items for assessing the level of patient satisfaction. RESULTS: A total of 1199 patients participated in the current study, 72.1 of them were female and 19.6 waited 10-20 minutes for receiving services. About 55.72 of the participants chose high and very high for the items of the inventory. Total satisfaction with the family physician program decreased with age (p-value=0.029).Moreover, total satisfaction did not show any significant differences in different groups in terms of sex, place of residence, education level and marital status. Also family physicians' sex did not affect patient satisfaction significantly. Based on results of regression model, an increase in patients' age by one year decreased their satisfaction by 0.12 and level of satisfaction in rural patients was lower than that in urban patients by 7.93. CONCLUSIONS: The level of patient satisfaction with family physician services was moderate, which mostly arose from the components of the family physician program and services such as the waiting time, costs, welfare facilities, accessibility and the service-providing team rather than patients' personal characteristics

Incorporation mechanism of colloidal TiO2 nanoparticles and their effect on properties of coatings grown on 7075 Al alloy from silicate-based solution using plasma electrolytic oxidation

Plasma electrolytic oxidation (PEO) was applied using a pulsed unipolar waveform to produce Al2O3-TiO2 composite coatings from sol electrolytic solutions containing colloidal TiO2 nanoparticles. The sol solutions were produced by dissolving 1, 3, and 5 g/L of potassium titanyl oxalate (PTO) in a silicate solution. Scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and Raman spectroscopy were applied to characterizing the coatings. Corrosion behavior of the coatings was investigated using polarization and impedance techniques. The results indicated that TiO2 enters the coating through all types of micro-discharging and is doped into the alumina phase. The higher level of TiO2 incorporation results in the decrease of surface micro-pores, while the lower incorporation shows a reverse effect. It was revealed that the higher TiO2 content makes a more compact outer layer and increases the inner layer thickness of the coating. Electrochemical measurements revealed that the coating obtained from the solution containing 3 g/L PTO exhibits higher corrosion performance than that obtained in the absence of PTO. The coating produced in the absence of PTO consists of gamma-Al2O3, delta-Al2O3 and amorphous phases, while alpha-Al2O3 is promoted by the presence of PTO

Identifying factors affecting destination choice of medical tourists: a systematic review of literature

Objective: Overseas travels in which improved health is the main component, “medical tourism”, has emerged as a new source of competitive advantage all over the world. The present study seeks to identify the factors that affect destination choice of medical tourists.Methods: We systematically searched relevant databases including Pub Med, Embase, Science Direct, Web of Science and Medline databases using terms “medical tourism” OR “health tourism”.Studies were identified and screened in accordance with the preferred Reporting Items for Systematic and Meta-Analyses (PRISMA) published in English or Farsi, determining factors that develop  country’s ability to become a preferred destination for outbound patients seeking healthcare services in foreign countries.Results: The search retrieved (1374) citation of which 18 studies were eligible.Across the eligible articles, 13 overarching themes including 75 that encourage medical tourists to choose a specific destination sub-themesemerged.Conclusions: Results of this study offer evidence for a comprehensive approach to strategic outreach and market expansion for medical tourism decision makers for attracting more medical tourists to their countries.Keywords: Medical tourism, health tourism, attractive factors, destination choic

Corrosion and wear resistance of coatings produced on AZ31 Mg alloy by plasma electrolytic oxidation in silicate-based K2TiF6 containing solution: Effect of waveform

In this research, plasma electrolytic oxidation coatings were prepared on AZ31 Mg alloy in a silicate-based solution containing K2TiF6 using bipolar and soft sparking waveforms with 10, 20, and 30% cathodic duty cycles. The coatings displayed a net-like surface morphology consisted of irregular micro-pores, micro-cracks, fused oxide particles, and a sintered structure. Due to the incorporation of TiO2 colloidal particles and the cathodic pulse repair effect, most of the micro-pores were sealed. Long-term corrosion performance of the coatings was investigated using electrochemical impedance spectroscopy during immersion in 3.5 wt.% NaCl solution up to 14 days. The coating grown by the soft sparking waveform with a 20% cathodic duty cycle having the lowest porosity (6.2%) and a sharp layer concentrated in F element at the substrate/coating interface shows the highest corrosion resistance. The friction coefficient of this coating has remained stable during the sliding even under 5 N normal load, showing relatively higher wear resistance than other coatings. The coating produced using the equivalent unipolar waveform, as the reference specimen, showed the highest friction coefficient and the lowest wear resistance despite its highest micro-hardness

Silicate and Hydroxide Concentration Influencing the Properties of Composite Al2 O3-TiO2 PEO Coatings on AA7075 Alloy

This work evaluates the effect of sodium meta-silicate pentahydrate (SMS) and potassium hydroxide concentrations on properties of Al2O3-TiO2 coatings produced through plasma electrolytic oxidation in a solution containing 3 g L−1 potassium titanyl oxalate, (PTO), using a unipolar waveform with constant current density. The surface and cross-section characteristics of PEO coatings including morphology, elemental distribution, and phase composition were evaluated using FESEM, EDS, and XRD techniques. Voltage-time response indicated the concentration of SMS and KOH had a significant effect on the duration of each stage of the PEO process. More cracks and pores were formed at the higher concentrated solutions that resulted in the incorporation of solution components especially Si into the coating inner parts. Ti is distributed throughout the coatings, but it had a dominant distribution in the Si-rich areas. The coating prepared in the electrolyte containing no silicate consisted of non-stoichiometric γ-Al2O3 and/or amorphous Al2O3 phase. Adding silicate into the coating electrolyte resulted in the appearance of α-Al2O3 besides the dominant phase of γ-Al2O3. The corrosion behaviour of the coatings was investigated using the EIS technique. It was found that the coating prepared in the presence of 3 g L−1 SMS and 2 g L−1 KOH, possessed the highest barrier resistance (~10 MΩ cm2), owing to a more compact outer layer, thicker inner layer along with appropriate dielectric property because this layer lacks the Si element. It was discovered that the incorporation of Ti4+ and especially Si4+ in the coating makes the dielectric loss in the coating

Unusual sites of bone involvement in Langerhans cell histiocytosis: a systematic review of the literature

Background: Langerhans cell histiocytosis (LCH) is a rare disease that originates from the uncontrolled proliferation and accumulation of bone marrow-derived immature myeloid dendritic cells. Dendritic cells are a type of histiocyte that play an important role in the human immune system and are found in the bone, skin, stomach, eyes, intestines, and lungs. Objective: This systematic review aimed to collect and report published case reports of rare bone disease caused by LCH to avoid misdiagnoses or delays in diagnosis. Methods: We systematically searched Scopus, PubMed, Embase, and Web of Sciences from August 1, 2000 to December 31, 2019. Studies reporting cases of LCH with rare bone involvement were included. Results: We identified 60 articles including 64 cases. Of the identified cases, 31 (48.4) involved children, and 33 (51.6) involved adults. Additionally, 46.9 (30 individuals) were from Asian countries. The mean age of the children was 7.6 ± 4.3 years and that of the adults was 36 ± 12 years. The findings indicated that unifocal bone involvements were the most prevalent form of the disease (68.7), and, overall, the skull and chest wall were the most commonly affected bones in both adults and children. The spine and long bones were the second most commonly affected bones in children, and the spine and jaw were the second most commonly affected bones in adults. Pain and swelling were the most frequent presenting signs among the investigated cases, and loss of consciousness, myelopathy, nerve palsy, visual loss, torticollis and clicking sounds were rare signs. Osteolytic lesions were the most frequent radiologic feature (62.5), and intracranial hemorrhage, fluid�fluid level, dura and intracranial extension and pathologic fractures were rare radiological features. Total excision, curettage and observation in the unifocal group of patients and systemic chemotherapy in the other groups (i.e., multifocal and multisystem) were the most frequent management approaches. The recovery rates of the unifocal and multifocal groups were 77.3 and 81.8, respectively, while that of the multisystem group was 55.5. The rates of recurrence and mortality in the multisystem group were 11 and were higher than those in the other groups. Conclusions: LCH is a rare disease that can affect any organ in the human body. However, bone is the most commonly involved organ, and rare bone involvements may be the first or only symptom of the disease due to the rarity of such lesions; a lack of familiarity with them may result in misdiagnosis or delayed diagnosis. © 2021, The Author(s)